Corruption Cards

Corruption Cards is a gameplay mod for the GZDoom source port by Mike Hill (Cutmanmike) that can provide many specific gameplay changes, depending on the player's choices. Groups of cards are presented to the player, from which they select the items to "corrupt" their game with.

First released on March 24, 2020, Corruption Cards has had substantial development, with Cutmanmike adding many clever features. It is well-regarded for its breadth and polish, winning a Cacoward in 2021. It has also become popular with YouTube and Twitch streamers, since the selection process and the sometimes dramatic effects can foster a more engaging viewer experience.

The latest version of the mod is 5.1c as of August 2023.

Gameplay
Corruption Cards is meant to be played on any given series of maps, whereupon a selection of cards will be displayed to the player at the start of each level. The player has to then make a choice between at least one of the cards present, which, upon being picked, will apply select gameplay modifications for the rest of the map. The cards have different ranks and they vary wildly in scope, effect and duration, and can range from minor oddities to large-scale effects that can potentially change the way an entire map is played. The number of cards available is determined by the game mode chosen, with the standard setup involving a maximum of three cards that can be chosen from on each map. Cards themselves are separated into those that affect only the duration of the current level and those that instead are applied permanently throughout a playthrough. In some cases, card effects may also be stacked or interact with one another, adding a further layer of complexity and uniqueness to each run of the mod. In most cases, the cards influence the various monsters in the level, with a significant portion of effects applying directly or indirectly to various monster types. In some other cases though, the level itself may be changed in some way, such as via the addition of toxic rain, or certain changes can also end up affecting weapons and other items that the player may find throughout a level.

By itself, Corruption Cards does not come with any dedicated levels, but it is built for maximum compatibility with as many mods as possible, including those using custom DeHackEd monsters, and other complex mods such as Doom Roguelike Arsenal and Doom CE. The mod has functionality that allows it to generate brand new cards for the custom enemies it detects, allowing for even more unpredictable scenarios in playthroughs undertaken with other compatible mods. Because of its fundamental mechanics, however, Corruption Cards is recommended to be played on mods featuring short-to-medium sized maps, rather than single maps or mods containing very large maps, although different results may be obtained through the mod's customization options.

Game modes
When starting a new game, Corruption Cards presents the player with two separate sets of options. The first is the game mode which will determine the overall rules of play, including the number of cards and how many of them will be permanent or temporary. Below is a list of all six game modes:


 * Standard: Considered to be the balanced and default playing mode, standard offers three new cards on each level, of which only one may be picked. Initially the card will only affect the current level, but every three maps a choice will have to be made to pick a permanent card between the three. Higher ranked cards generally only appear later on during a playthrough.
 * Hardcore: This is a harder version and is similar to standard in that three cards are offered at the beginning of each level, but it presents two major differences in that each card picked will have its effects be permanent throughout a playthrough, and cards of all ranks have the potential to appear from the beginning, with lower rank cards being gradually phased out during a playthrough.
 * Chaos: This is akin to a pure random mode, in that there is no selection of cards to choose from as only a single card is dealt to the player at the start of each map. Much like hardcore mode, all card effects are permanent, but in chaos there is no difficulty scaling, and all cards from all ranks can consistently appear from beginning to end.
 * Daily challenge: This special mode offers a pre-set seed containing already decided cards and effects for a playthrough, which will change every day and be consistent throughout each unedited copy of the mod. This allows multiple people to tackle the same "challenge run", although differences may still apply if Corruption Cards is loaded with a mod that offers custom monsters.
 * Custom: As the name implies, this set is all about player choice, as it allows to customize the types of cards that are dealt at the start of each map, their rank and difficulty progression, as well as the number of cards the player may be offered and choose for each map (up to a maximum of eight).
 * Master: This is an initially hidden game mode that shows up after the player has collected 60 cards in the other modes. It is similar to the chaos mode in that it only allows one card at the start of each map of any random type, but the key difference is that the effect and type of the card will not be revealed to the player at the start, making for extremely unpredictable runs. Further, after 12 maps, an additional "wild card" will be chosen.

In turn, after selecting the game mode, the player may then choose between four different types of card sets:


 * Regular: Containing 226 card types, this is the regular card set, containing all types of monster enhancements and modifications to the game world.
 * Balanced: This card set is focused more tightly on relatively more minor effects that don't risk potentially ruining a playthrough on maps that end up being too poorly fitting for the regular set, and is thus recommended for WADs that do not properly work with the first mode.
 * New friends: This card set is specifically focused on cards that add new monsters to the levels, whether they appear in place of already placed monsters or through other effects, with no other gameplay alterations.
 * Science project: This card set focuses exclusively on cards that alter or enhance monster properties, thus making individual enemies more dangerous in unpredictable ways without modifying any other parts of the core gameplay.
 * Treacherous world: This card set foregoes modifying monsters entirely and instead solely focuses on cards that alter the gameplay on the map, such as harmful weather or turrets or explosion effects that can be a hazard to players and monsters alike.

Card effects
Befitting to its name, the main purpose of Corruption Cards is to provide a choice of what essentially boils down to maluses on each map start. There are no cards in the game that outright provide a benefit, although some may prove useful in specific and isolated circumstances, such as a card making a monster explode allowing the player to damage other monsters in said explosion. Generally speaking, the player has to strategically choose each card at the start of the match that proves the least amount of danger either for that specific map, or due to a combination of other cards already picked. For example, multiple cards may affect the same enemy and thus that enemy may be boosted multiple times, and certain effects provided by cards may also stack, so even if the same card appears twice it can result in even stronger effects than when it was picked the first time.

The cards themselves follow general themes, as for example, it is possible to find a card that increases the damage dealt by either imps, zombies, Hell nobles and other types of enemies when they are low on health. However, only one category of this enemy will be affected by each card, and so a card that makes barons of Hell and Hell knights shoot railgun projectiles will not affect cacodemons or imps even though these monsters have an equivalent card applying the same effect. Other effects are instead unique to each monster, or simply introduce new monsters and dangers to the player in various ways, such as teleporting a random monster in the map every time a player kills 16 other monsters, or having totems appear that buff up already placed monsters. Certain cards instead affect items, which may jump away from a player trying to pick them up, or environmental hazards such as acid rain, earthquake, a downpour of blood that powers up monsters underneath it, and more.

In order to keep track of the various effects accumulated during a playthrough, Corruption Cards offers a section on the menu called the Card Compendium: this allows a player to view all the cards previously collected during a run, to read up on its effects in greater detail than during normal play and on some other attributes, such as whether the effects can be stacked or not. Additionally, it is also possible to view the current effects during a run by binding a key to the stats screen in the options menu.

Trivia

 * A card called "Rescue Mission" forces you to find Daisy hidden somewhere in the level, otherwise the monsters in the next level will gain a random power. Daisy runs in circles and makes rabbit noises.
 * A card called "Fluffy Gifts" make monsters of a certain type to have a chance to add Hissy (called "Cacodemon Plush toy" in game) to the player's inventory. She is a weapon (slot is chosen randomly), the player carries her in their hand and can throw her like a grenade. Hissy does no damage and just clogs up a weapon slot.
 * A card called "Mystery Eggs" randomly spawns alien-looking eggs throughout the level that can be destroyed, spawning random monsters (or their small-sized weak versions) or powerups. This is another way to obtain Hissy. Some of the eggs can also spawn fake Daisy.